arch/x86/kernel/paravirt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*  Paravirtualization interfaces
   3     Copyright (C) 2006 Rusty Russell IBM Corporation
   4
   5
   6     2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
   7 */
   8
   9 #include <linux/errno.h>
  10 #include <linux/init.h>
  11 #include <linux/export.h>
  12 #include <linux/efi.h>
  13 #include <linux/bcd.h>
  14 #include <linux/highmem.h>
  15 #include <linux/kprobes.h>
  16 #include <linux/pgtable.h>
  17 #include <linux/static_call.h>
  18
  19 #include <asm/bug.h>
  20 #include <asm/paravirt.h>
  21 #include <asm/debugreg.h>
  22 #include <asm/desc.h>
  23 #include <asm/setup.h>
  24 #include <asm/time.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/irq.h>
  27 #include <asm/delay.h>
  28 #include <asm/fixmap.h>
  29 #include <asm/apic.h>
  30 #include <asm/tlbflush.h>
  31 #include <asm/timer.h>
  32 #include <asm/special_insns.h>
  33 #include <asm/tlb.h>
  34 #include <asm/io_bitmap.h>
  35
  36 /*
  37  * nop stub, which must not clobber anything *including the stack* to
  38  * avoid confusing the entry prologues.
  39  */
  40 extern void _paravirt_nop(void);
  41 asm (".pushsection .entry.text, \"ax\"\n"
  42      ".global _paravirt_nop\n"
  43      "_paravirt_nop:\n\t"
  44      ASM_ENDBR
  45      ASM_RET
  46      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  47      ".type _paravirt_nop, @function\n\t"
  48      ".popsection");
  49
  50 /* stub always returning 0. */
  51 asm (".pushsection .entry.text, \"ax\"\n"
  52      ".global paravirt_ret0\n"
  53      "paravirt_ret0:\n\t"
  54      ASM_ENDBR
  55      "xor %" _ASM_AX ", %" _ASM_AX ";\n\t"
  56      ASM_RET
  57      ".size paravirt_ret0, . - paravirt_ret0\n\t"
  58      ".type paravirt_ret0, @function\n\t"
  59      ".popsection");
  60
  61
  62 void __init default_banner(void)
  63 {
  64         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  65                pv_info.name);
  66 }
  67
  68 /* Undefined instruction for dealing with missing ops pointers. */
  69 noinstr void paravirt_BUG(void)
  70 {
  71         BUG();
  72 }
  73
  74 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
  75                                     unsigned long addr, unsigned len)
  76 {
  77         __text_gen_insn(insn_buff, CALL_INSN_OPCODE,
  78                         (void *)addr, target, CALL_INSN_SIZE);
  79         return CALL_INSN_SIZE;
  80 }
  81
  82 #ifdef CONFIG_PARAVIRT_XXL
  83 /* identity function, which can be inlined */
  84 u64 notrace _paravirt_ident_64(u64 x)
  85 {
  86         return x;
  87 }
  88 #endif
  89
  90 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
  91
  92 void __init native_pv_lock_init(void)
  93 {
  94         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  95                 static_branch_disable(&virt_spin_lock_key);
  96 }
  97
  98 unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr,
  99                             unsigned int len)
 100 {
 101         /*
 102          * Neat trick to map patch type back to the call within the
 103          * corresponding structure.
 104          */
 105         void *opfunc = *((void **)&pv_ops + type);
 106         unsigned ret;
 107
 108         if (opfunc == NULL)
 109                 /* If there's no function, patch it with paravirt_BUG() */
 110                 ret = paravirt_patch_call(insn_buff, paravirt_BUG, addr, len);
 111         else if (opfunc == _paravirt_nop)
 112                 ret = 0;
 113         else
 114                 /* Otherwise call the function. */
 115                 ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
 116
 117         return ret;
 118 }
 119
 120 struct static_key paravirt_steal_enabled;
 121 struct static_key paravirt_steal_rq_enabled;
 122
 123 static u64 native_steal_clock(int cpu)
 124 {
 125         return 0;
 126 }
 127
 128 DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
 129 DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock);
 130
 131 void paravirt_set_sched_clock(u64 (*func)(void))
 132 {
 133         static_call_update(pv_sched_clock, func);
 134 }
 135
 136 /* These are in entry.S */
 137 static struct resource reserve_ioports = {
 138         .start = 0,
 139         .end = IO_SPACE_LIMIT,
 140         .name = "paravirt-ioport",
 141         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 142 };
 143
 144 /*
 145  * Reserve the whole legacy IO space to prevent any legacy drivers
 146  * from wasting time probing for their hardware.  This is a fairly
 147  * brute-force approach to disabling all non-virtual drivers.
 148  *
 149  * Note that this must be called very early to have any effect.
 150  */
 151 int paravirt_disable_iospace(void)
 152 {
 153         return request_resource(&ioport_resource, &reserve_ioports);
 154 }
 155
 156 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 157
 158 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 159 {
 160         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 161
 162         this_cpu_write(paravirt_lazy_mode, mode);
 163 }
 164
 165 static void leave_lazy(enum paravirt_lazy_mode mode)
 166 {
 167         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 168
 169         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 170 }
 171
 172 void paravirt_enter_lazy_mmu(void)
 173 {
 174         enter_lazy(PARAVIRT_LAZY_MMU);
 175 }
 176
 177 void paravirt_leave_lazy_mmu(void)
 178 {
 179         leave_lazy(PARAVIRT_LAZY_MMU);
 180 }
 181
 182 void paravirt_flush_lazy_mmu(void)
 183 {
 184         preempt_disable();
 185
 186         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 187                 arch_leave_lazy_mmu_mode();
 188                 arch_enter_lazy_mmu_mode();
 189         }
 190
 191         preempt_enable();
 192 }
 193
 194 #ifdef CONFIG_PARAVIRT_XXL
 195 void paravirt_start_context_switch(struct task_struct *prev)
 196 {
 197         BUG_ON(preemptible());
 198
 199         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 200                 arch_leave_lazy_mmu_mode();
 201                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 202         }
 203         enter_lazy(PARAVIRT_LAZY_CPU);
 204 }
 205
 206 void paravirt_end_context_switch(struct task_struct *next)
 207 {
 208         BUG_ON(preemptible());
 209
 210         leave_lazy(PARAVIRT_LAZY_CPU);
 211
 212         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 213                 arch_enter_lazy_mmu_mode();
 214 }
 215
 216 static noinstr unsigned long pv_native_read_cr2(void)
 217 {
 218         return native_read_cr2();
 219 }
 220
 221 static noinstr void pv_native_write_cr2(unsigned long val)
 222 {
 223         native_write_cr2(val);
 224 }
 225
 226 static noinstr unsigned long pv_native_get_debugreg(int regno)
 227 {
 228         return native_get_debugreg(regno);
 229 }
 230
 231 static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
 232 {
 233         native_set_debugreg(regno, val);
 234 }
 235
 236 static noinstr void pv_native_irq_enable(void)
 237 {
 238         native_irq_enable();
 239 }
 240
 241 static noinstr void pv_native_irq_disable(void)
 242 {
 243         native_irq_disable();
 244 }
 245 #endif
 246
 247 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 248 {
 249         if (in_interrupt())
 250                 return PARAVIRT_LAZY_NONE;
 251
 252         return this_cpu_read(paravirt_lazy_mode);
 253 }
 254
 255 struct pv_info pv_info = {
 256         .name = "bare hardware",
 257 #ifdef CONFIG_PARAVIRT_XXL
 258         .extra_user_64bit_cs = __USER_CS,
 259 #endif
 260 };
 261
 262 /* 64-bit pagetable entries */
 263 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 264
 265 struct paravirt_patch_template pv_ops = {
 266         /* Cpu ops. */
 267         .cpu.io_delay           = native_io_delay,
 268
 269 #ifdef CONFIG_PARAVIRT_XXL
 270         .cpu.cpuid              = native_cpuid,
 271         .cpu.get_debugreg       = pv_native_get_debugreg,
 272         .cpu.set_debugreg       = pv_native_set_debugreg,
 273         .cpu.read_cr0           = native_read_cr0,
 274         .cpu.write_cr0          = native_write_cr0,
 275         .cpu.write_cr4          = native_write_cr4,
 276         .cpu.wbinvd             = native_wbinvd,
 277         .cpu.read_msr           = native_read_msr,
 278         .cpu.write_msr          = native_write_msr,
 279         .cpu.read_msr_safe      = native_read_msr_safe,
 280         .cpu.write_msr_safe     = native_write_msr_safe,
 281         .cpu.read_pmc           = native_read_pmc,
 282         .cpu.load_tr_desc       = native_load_tr_desc,
 283         .cpu.set_ldt            = native_set_ldt,
 284         .cpu.load_gdt           = native_load_gdt,
 285         .cpu.load_idt           = native_load_idt,
 286         .cpu.store_tr           = native_store_tr,
 287         .cpu.load_tls           = native_load_tls,
 288         .cpu.load_gs_index      = native_load_gs_index,
 289         .cpu.write_ldt_entry    = native_write_ldt_entry,
 290         .cpu.write_gdt_entry    = native_write_gdt_entry,
 291         .cpu.write_idt_entry    = native_write_idt_entry,
 292
 293         .cpu.alloc_ldt          = paravirt_nop,
 294         .cpu.free_ldt           = paravirt_nop,
 295
 296         .cpu.load_sp0           = native_load_sp0,
 297
 298 #ifdef CONFIG_X86_IOPL_IOPERM
 299         .cpu.invalidate_io_bitmap       = native_tss_invalidate_io_bitmap,
 300         .cpu.update_io_bitmap           = native_tss_update_io_bitmap,
 301 #endif
 302
 303         .cpu.start_context_switch       = paravirt_nop,
 304         .cpu.end_context_switch         = paravirt_nop,
 305
 306         /* Irq ops. */
 307         .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
 308         .irq.irq_disable        = __PV_IS_CALLEE_SAVE(pv_native_irq_disable),
 309         .irq.irq_enable         = __PV_IS_CALLEE_SAVE(pv_native_irq_enable),
 310         .irq.safe_halt          = native_safe_halt,
 311         .irq.halt               = native_halt,
 312 #endif /* CONFIG_PARAVIRT_XXL */
 313
 314         /* Mmu ops. */
 315         .mmu.flush_tlb_user     = native_flush_tlb_local,
 316         .mmu.flush_tlb_kernel   = native_flush_tlb_global,
 317         .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
 318         .mmu.flush_tlb_multi    = native_flush_tlb_multi,
 319         .mmu.tlb_remove_table   =
 320                         (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 321
 322         .mmu.exit_mmap          = paravirt_nop,
 323         .mmu.notify_page_enc_status_changed     = paravirt_nop,
 324
 325 #ifdef CONFIG_PARAVIRT_XXL
 326         .mmu.read_cr2           = __PV_IS_CALLEE_SAVE(pv_native_read_cr2),
 327         .mmu.write_cr2          = pv_native_write_cr2,
 328         .mmu.read_cr3           = __native_read_cr3,
 329         .mmu.write_cr3          = native_write_cr3,
 330
 331         .mmu.pgd_alloc          = __paravirt_pgd_alloc,
 332         .mmu.pgd_free           = paravirt_nop,
 333
 334         .mmu.alloc_pte          = paravirt_nop,
 335         .mmu.alloc_pmd          = paravirt_nop,
 336         .mmu.alloc_pud          = paravirt_nop,
 337         .mmu.alloc_p4d          = paravirt_nop,
 338         .mmu.release_pte        = paravirt_nop,
 339         .mmu.release_pmd        = paravirt_nop,
 340         .mmu.release_pud        = paravirt_nop,
 341         .mmu.release_p4d        = paravirt_nop,
 342
 343         .mmu.set_pte            = native_set_pte,
 344         .mmu.set_pmd            = native_set_pmd,
 345
 346         .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
 347         .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,
 348
 349         .mmu.set_pud            = native_set_pud,
 350
 351         .mmu.pmd_val            = PTE_IDENT,
 352         .mmu.make_pmd           = PTE_IDENT,
 353
 354         .mmu.pud_val            = PTE_IDENT,
 355         .mmu.make_pud           = PTE_IDENT,
 356
 357         .mmu.set_p4d            = native_set_p4d,
 358
 359 #if CONFIG_PGTABLE_LEVELS >= 5
 360         .mmu.p4d_val            = PTE_IDENT,
 361         .mmu.make_p4d           = PTE_IDENT,
 362
 363         .mmu.set_pgd            = native_set_pgd,
 364 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 365
 366         .mmu.pte_val            = PTE_IDENT,
 367         .mmu.pgd_val            = PTE_IDENT,
 368
 369         .mmu.make_pte           = PTE_IDENT,
 370         .mmu.make_pgd           = PTE_IDENT,
 371
 372         .mmu.dup_mmap           = paravirt_nop,
 373         .mmu.activate_mm        = paravirt_nop,
 374
 375         .mmu.lazy_mode = {
 376                 .enter          = paravirt_nop,
 377                 .leave          = paravirt_nop,
 378                 .flush          = paravirt_nop,
 379         },
 380
 381         .mmu.set_fixmap         = native_set_fixmap,
 382 #endif /* CONFIG_PARAVIRT_XXL */
 383
 384 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
 385         /* Lock ops. */
 386 #ifdef CONFIG_SMP
 387         .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
 388         .lock.queued_spin_unlock        =
 389                                 PV_CALLEE_SAVE(__native_queued_spin_unlock),
 390         .lock.wait                      = paravirt_nop,
 391         .lock.kick                      = paravirt_nop,
 392         .lock.vcpu_is_preempted         =
 393                                 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
 394 #endif /* SMP */
 395 #endif
 396 };
 397
 398 #ifdef CONFIG_PARAVIRT_XXL
 399 NOKPROBE_SYMBOL(native_load_idt);
 400 #endif
 401
 402 EXPORT_SYMBOL(pv_ops);
 403 EXPORT_SYMBOL_GPL(pv_info);